The initial step in the infectious cycle of the single-stranded DNA phage øX174 is the synthesis of a DNA strand complementary to the infecting viral DNA producing a duplex molecule, the parental replicative form (RF). Electron micrographic examination of parental RF produced from viruses exposed to ultra-violet (UV) light suggests that synthesis begins at only one site. However, in vitro results and some recent reports of in vivo experiements contradict that interpretation.
Using restriction enzymes we have re-examined the incomplete RF made from UV-damaged phage. Parental RF made in vivo from viruses exposed to various UV doses were purified by velocity sedimentation and benzoylated naphthoylated diethylaminoethylcellulose column chromatography. The incomplete parental RF were digested with a restriction enzyme and the fragments separated by by gel electrophoresis. The genetic location of the new DNA was determined from the relative amount of label appearing at each fragment position.
Readioactive label was not uniformly distributed among the DNA fragments, but neither was there a simple sequence of increasing radioactivity. We conclude that initiation was not random but occurred at several sites. The data do not exclude the possibility that a single initiation site was employed on each template but that the site varied from template to template.
Anthony J. Zuccarelli
Leonard R. Brand
Robert L. Nutter
Master of Arts (MA)
Year Degree Awarded
Date (Title Page)
Library of Congress/MESH Subject Headings
Bacteriophages -- analysis; DNA Restriction Enzymes; DNA Single-Stranded
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This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.
Bogardus, Alicia Morales, "Restriction Enzyme Analysis of Incomplete Parental Replicative Forms of øX174" (1979). Loma Linda University Electronic Theses, Dissertations & Projects. 1396.
Loma Linda University Electronic Theses and Dissertations
Loma Linda University. Del E. Webb Memorial Library. University Archives